3-D printing using intermediate transfer belt and curable polymers

ABSTRACT

3-D printing transfers build material and support from an intermediate transfer belt (ITB) to a platen. The build material is the same as the support material, except that the build material includes a photoinitiator and the support material does not. The platen moves to make contact with the ITB, and the ITB transfers successive layers of build material and support material each time the platen contacts the ITB. The platen and a portion of the ITB that is adjacent the platen are heated prior to the platen contacting the ITB, and the same is exposed so as to crosslink polymers of build material, without crosslinking polymers of support material. The polymers of build material being crosslinked and the polymers of support material not being crosslinked makes the support material selectively soluble in a solvent.

BACKGROUND

Systems and methods herein generally relate to three dimensional (3-D)printing processes that use ultra-violet (UV) curable polymers.

Three-dimensional printing can produce objects using, for example,ink-jet or electrostatic printers. In one exemplary three-stage process,a pulverulent material is printed in thin layers, a UV-curable liquid isprinted on the pulverulent material, and finally each layer is hardenedusing a UV light source. These steps are repeated layer-by-layer.Support material generally comprises acid-, base- or water-solublepolymers, which can be selectively rinsed from the build material after3-D printing is complete.

Therefore, production of parts using a three-dimensional (3-D) processis predicated on the deposition of a build material, from which the partitself is produced, and a support material, which fill voids andcavities in the part and whose function is to provide mechanical supportto the build material. The support material is removed to leave behindonly the part that is desired. One way to approach this is to dissolveaway the support material.

SUMMARY

Exemplary three-dimensional (3-D) printers herein include (among othercomponents, an intermediate transfer belt (ITB), a first photoreceptortransferring a first material (e.g., build material) to the ITB, and asecond photoreceptor transferring a second material (e.g., supportmaterial) to the ITB. Exposure and development devices transfer buildmaterial to the first photoreceptor and support material to the secondphotoreceptor. The build material is the same as the support material,except that the build material includes a photoinitiator and supportmaterial does not include the photoinitiator. The build material and thesupport material both comprise ultra-violet (UV) crosslinkable polymertoners that use the photoinitiator to crosslink. The layer of the firstmaterial and the second material is on a discrete area of the ITB and isin a pattern.

Such printers also include a platen moving relative to the ITB to makecontact with the ITB. The ITB transfers successive layers of buildmaterial and support material to the platen each time the platencontacts the ITB, and this process eventually builds a 3-D object on theplaten.

At least one heater is also included in such structures, and the heaterheats the platen and heats a portion of the ITB that is adjacent theplaten to the glass transition temperature of build material and supportmaterial prior to the platen contacting the ITB. The heater furtherheats build material and support material on the platen to a temperaturebetween the glass transition temperature and the melting temperature ofbuild material and support material after the ITB transfers buildmaterial and support material to the platen, and this fuses the buildmaterial and support material to previously transferred material on theplaten.

Such printers also include a light (e.g., UV light source). The platenmoves from the ITB to the light, and then the light exposes buildmaterial and support material on the platen after each time the platencontacts the ITB, and this crosslinks polymers of the build materialwithout crosslinking polymers of the support material. Various systemsherein include a rinsing station that applies solvent to the 3-D objectto dissolve only the support material and to leave the build materialunaffected. The polymers of build material being crosslinked and thepolymers of support material not being crosslinked makes supportmaterial selectively soluble in different solvents than the buildmaterial.

Methods of performing 3-D printing herein transfer first material (e.g.,build material) to a first photoreceptor and second material (e.g.,support material) to a second photoreceptor using exposure anddevelopment devices, and then transfer build material from the firstphotoreceptor and support material from the second photoreceptor to anintermediate transfer belt (ITB). The build material is the same as thesupport material, except that the build material includes aphotoinitiator and the support material does not include thephotoinitiator. For example, the build material and support material cancomprise ultra-violet (UV) crosslinkable polymer toners that use thephotoinitiator to crosslink.

Such processes move a platen relative to the ITB to be adjacent the ITB.These methods also heat the platen and heat a portion of the ITB that isadjacent the platen using a heater. After heating, such methods move theplaten to contact ITB. Successive contacts between the ITB and platentransfer successive layers of build material and support material to theplaten (each time the platen contacts the ITB) and this successivelybuilds the 3-D object on the platen.

Methods herein move the platen from the ITB to a light (e.g., UV lightsource) and then expose the build material and support material usingthe light, after each time the platen contacts the ITB, so as tocrosslink polymers of build material, without crosslinking polymers ofsupport material.

Subsequent processing removes the 3-D object of build material andsupport material from the platen after all the successive layers aretransferred, and applies solvent to the 3-D object using a rinsingstation to dissolve only the support material and to leave the buildmaterial unaffected. The polymers of build material being crosslinkedand the polymers of support material not being crosslinked make thesupport material selectively soluble in the solvent (relative to thebuild material).

These and other features are described in, or are apparent from, thefollowing detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

Various exemplary systems and methods are described in detail below,with reference to the attached drawing figures, in which:

FIG. 1 is a chart illustrating the idealized melt rheology curve of thematerials herein;

FIG. 2 is a schematic diagram illustrating devices herein;

FIG. 3 is a schematic diagram illustrating devices herein;

FIG. 4 is a schematic diagram illustrating devices herein;

FIG. 5 is a schematic diagram illustrating devices herein;

FIG. 6 is a schematic diagram illustrating devices herein;

FIG. 7 is a schematic diagram illustrating devices herein;

FIG. 8 is a schematic diagram illustrating devices herein;

FIG. 9 is a schematic diagram illustrating devices herein;

FIG. 10 is a schematic diagram illustrating devices herein;

FIG. 11 is a flow diagram of various methods herein;

FIG. 12 is a schematic diagram illustrating devices herein;

FIG. 13 is a schematic diagram illustrating devices herein; and

FIG. 14 is a schematic diagram illustrating devices herein.

DETAILED DESCRIPTION

As mentioned above, some 3-D processes are predicated on layer-by-layertransfuse of the build and support material, and the materials may havesimilar melt rheological properties and hence similar chemicalstructures. This makes separation by dissolution a difficult task.

Therefore, the systems and methods herein provide 3-D parts that may befabricated by any of multiple additive manufacturing processes in commonusage in which the part is built up by sequential layer-by-layerdeposition of a suitable plastic build material and plastic support. Ingeneral 3-D parts are built from a digital representation of the partwhich is divided into multiple horizontal slices. Instructions forprinting individual layers are sent by a controller to the print processto form any given layer.

One exemplary 3-D printing process where the materials may have similarmelt rheological properties (and hence similar chemical structures)develops build and support toner materials onto an intermediate transferbelt (ITB). The developed layers of these toner materials are transfusedto a moving platen. The developed layer and ITB are locally heated tobring the developed layer to a “tacky” state prior to transfuse (i.e.,to a temperature higher than the glass transition temperature (Tg) butshort of the melt or fuse temperature Tm of the toner resin). A heatedplaten (heated to approximately the same temperature) is then contactedsynchronously with the tacky layer as it translates through theITB-platen nip. Thus, rather than being transferred electrostatically(based on toner/belt charge differences), it is the tacky nature of thedeveloped layer and heated platen (or previously transferred developedlayers) that causes the developed layer to transfer to the platen (orpreviously transferred developed layers). The platen is heated to keepthe toner in a tacky state as it contacts the heated toner/ITBinterface, and doing so allows the toner layer to separate from the ITBand transfer under pressure to the platen surface which may containpreviously deposited layers.

A post transfuse heating of the layer(s) is then effected to fuse thelast layer to the previous layers. Finally a cooling step to bring thetemperature of the layer(s) back down to the temperature at which thetoner layers are in a tacky state. The platen location is then recycledback to a home position from which it awaits the arrival of the nextlayer. Repetition of this process in principle allows the build ofthicker layers from which a part may be fabricated.

Many 3-D printing processes provide for co-deposition of a “support”layer which fills in the voids in the part to be produced in order tosupport the nascent part mechanically. One aspect of the supportmaterial is that it has nearly the same melt rheology as the buildmaterial in such 3-D printers. The melt rheology requirements can beunderstood by considering the idealized melt rheology curve for ahypothetical toner resin as shown in FIG. 1. In the initial heating ofthe developed layer on the ITB as well as the heating of the alreadyformed layers on the platen to the tacky state the toner resin must beheated slightly above Tg but must remain well below Tm so that theintegrity of the layers on the platen is maintained during transfuse andthe integrity of the transferring layer is also maintained. During thepost transfer step a temperature closer to Tm must be imparted to thelayers to fuse the uppermost layer to the layers below. So given aparticular pre-transfer temperature it is desirable that both thesupport and build material be in a similar state of tackiness and thatthe melt points for both be similar as well. This implies that the meltrheology curves for both build and support material is rather similar,otherwise there will be a loss of latitude in the temperature set pointsand poor transfuse of one or the other material. This requirement setsup strict limitations in the selection of support and build material,i.e. additional work is required to tune the resin chemical structures(e.g. molecular weight, nature of functional groups) to achieve similarmelt rheology curves for the two materials.

One general approach to separating the support from the build materialis by taking advantage of differences in solubility of the twomaterials. One would like to make the support material soluble in asolvent which will not dissolve the build material. Generally speakingthe latter condition is at odds with the requirement that the meltrheologies be similar. Similar melt rheologies implies similar chemicalstructures (molecular weight, functional groups) while the solubilitydisparity implies different chemical structures (different molecularweights and functional groups).

The systems and methods described herein reconcile differingrequirements for the build and support material, while improving themechanical properties (strength, impact resistance, etc.) of the supportmaterial made from current toners and resins. With systems and methodsherein, the build and support material can be fabricated from a UVradiation curable toner material with the difference being that thesupport material does not contain a photoinitiator required to make thetoner crosslinkable. Because the photoinitiator is present at very lowloading it has little to no effect on the melt rheology of the baselineresin. Hence, both support and build material can have nearly identicalmelt rheology properties, and can be an excellent pair of materials fortransfuse.

Crosslinking renders materials/polymers insoluble, thus a solvent whichwill dissolve the uncrosslinked toner resin will not dissolve thecrosslinked toner resin. This results in the support material beingseparable from the build material as desired. The process of UV curingthe build material is incorporated directly in the 3-D process used tobuild up and fuse together the layers of the build material.

Exemplary UV curable toner contain a resin with ethylenic unsaturation(double bonds) in the resin backbone structure, an optional crosslinkingagent which bonds adjacent polymer strands together and a UVphotoinitiator. In the materials described below the crosslinking agentis omitted as the polymer backbone of the toner resin contains ethylenicunsaturation which can achieve the desired crosslinking with adjacentpolymer backbones. Notwithstanding this, various high temperature stablecrosslinking agents can also be incorporated into the build materialtoner resin, if desired.

Many toners are made by the phase inversion process orEmulsion-Aggregation (EA process). This process results in toners with avery predictable particle size and shape. Potential toner resinscontaining unsaturation include those previously disclosed in U.S. Pat.Nos. 7,851,549 and in 7,250,238. These materials include (propoxylatedbisphenol-A-co-fumarate), poly(ethoxylatedbisphenol-A-co-fumarate),poly(butyloxylated bisphenol-co-fumarate), poly(co-propoxylatedbisphenol-co-ethoxylated bisphenol-co-fumarate), poly(1,2-propylenefumarate), poly(propoxylated bisphenol-co-maleate),poly(ethoxylatedbisphenol-co-maleate), poly(butyloxylatedbisphenol-co-maleate), poly(co-propoxylated bisphenol-co-ethoxylatedbisphenol-co-maleate), poly(1,2-propylene maleate), poly(propoxylatedbisphenol-co-itaconate), poly(ethoxylatedbisphenol-co-itaconate),poly(butyloxylated bisphenol co-itaconate), poly(co-propoxylatedbisphenol co-ethoxylated bisphenol co-itaconate), andpoly(1,2-propyleneitaconate).

Examples of UV-photoinitiators include 2-hydroxy-2-methyl1-phenyl-1-propanone available from various chemical companies;1-hydroxycyclohexylphenyl ketone;2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butan-1-one;2,2-dimethoxy-2-phenylacetophemorpholinyl)-1-propanone. Additionalexamples of photoinitiators from various chemical companies include butare not limited to 2-hydroxy-2-methyl-1-phenyl-propan-1-one (HMPP);2,4,6-trimethylbenzoyl diphenylphosphine oxide (TPO); 50-50 Blend ofHMPP and TPO; 2-methyl-1 [4-(methylthio)phenyl]-2-morpholinopropan-1-one (MMMP); and 2,2-dimethoxy-2-phenyl acetophenone (BDK).Examples of photoinitiators also, include, but are not limited to,2,4,6-trimethylbenzoyl diphenyl phosphine oxide (Lucirin TPO);alphahydroxyketone; and 2-hydroxy-2-methyl-phenyl-1-propane.

FIG. 1 is a graph illustrating that Young's Modulus (related toviscosity) of a toner resin is a strong function of temperature. Thetoner resin starts to soften at the glass transition temperature (Tg),below which the material is rather stiff and independent of temperatureas shown by the plateau in the curve. Increasing temperature beyond Tgcauses the resin to soften further until it flows relatively easily,effectively the melting point Tm of the resin.

FIG. 2 is a schematic diagram illustrating devices herein that use anITB 110 supported on rotating rollers 112, heat, and UV light curing toperform 3-D printing. A first development device 116 transfers buildmaterial 104 (by electrostatic toner-based printing processing) to theITB 110, and a second development device 114 transfers support materialto the ITB 110 on top of the previously formed build material 104 (bythe same electrostatic toner-based printing processing) to formdeveloped layers 102 on the ITB 110. Item 132 is a charge generator thatcreates a charge on the opposite side of the ITB 110 in order to drawthe build and support material from the development devices 116, 114 tothe ITB 110. Thus, developed layers 102 in the drawings are acombination of support material and build material. The developed layers102 of the first material and the second material are each on a discretearea of the ITB and are in a pattern. As the developed layers 102approach a transfuse nip 130 (as the ITB moves as shown by arrows) thedeveloped layers 102 and ITB 110 are heated by a heater 120 (e.g., aninfrared heater) to just above the Tg of the support and build materialsto render both the support and build materials in the developed layers102 tacky.

While the drawings only illustrate 2 development devices 116, 114, thoseordinarily skilled in the art would understand that many moredevelopment devices could be utilized to provide different types anddifferent colors of different build material and different supportmaterial. Such build and support material are printed in a pattern onthe ITB by each separate development device, and combine together in thedeveloped layers 102 to represent a specific pattern having apredetermined length. Thus, each of the developed layers 102 has aleading edge 134 oriented toward the processing direction in which theITB 110 is moving (represented by arrows next to the ITB 110 in FIGS.2-6) and a trailing edge 136 opposite the leading edge 134.

As shown in FIG. 3, the platen 118 (that may already contain somepreviously formed developed layers 102, shown as a partially formed part106) moves toward the transfuse nip 130 so as to contact the heatedportion of the ITB 110. At the transfuse nip 130, the leading edge 134of the developed layer 102 within the transfuse nip 130 begins to betransferred to a corresponding location of the platen 118 or partiallyformed part 106 that is being built, layer-by-layer. As shown in FIG. 3,the platen 118 moves to contact the developed layers 102 on the ITB 110at a location where the leading edge 134 of the developed layer 102 isat the lowest location of the roller of the transfuse nip 130. Thus, inthis example, the trailing edge 136 of the developed layer 102 has notyet reached the transfuse nip 130 and has not, therefore, yet beentransferred to the platen 118 or partially formed part 106.

As shown in FIG. 4, the platen 118 moves synchronously with the ITB 110(moves at the same speed and the same direction as the ITB 110) to allowthe developed layers 102 to transfer cleanly to the platen 118 orpartially formed part 106 without smearing. Wax (which is present inemulsion-aggregation toners) is present in the developed layers 102 andassists the tacky developed layers 102 parting from the ITB 110. In FIG.4, the trailing edge 136 of the developed layer 102 is the only portionthat has not yet reached the transfuse nip 130 and has not, therefore,been transferred to the platen 118 or partially formed part 106.

Then, as shown in FIG. 5, as the ITB 110 moves in the processingdirection, the platen 118 moves at the same speed and in the samedirection as the ITB 110 (shown in FIG. 4) until the trailing edge 136of the developed layer 102 reaches the bottom of the roller of thetransfuse nip 130 (shown in FIG. 11) at which point the platen 118 movesaway from the ITB 110 and over to the heater 122 and UV light source124, as shown in FIG. 6. This synchronous movement between the platen118 and the ITB 110 causes the pattern of support and build materials(102) that is printed by the development devices 116, 114 to betransferred precisely from the ITB 110 to the platen 118 or partiallyformed part 106.

Thus, as shown in FIG. 6, following transfuse of the developed layer 102to the platen 118, the platen 118 moves away from the transfuse nip 130and moves to a position to receive heat from another heater 122 (e.g.,infrared heat source). As shown in FIG. 6, additional heat from item 122is applied to the most recently transferred developed layer 102 on theprevious developed layers 106 on the platen 118 to fuse the developedlayer 102 to those previous developed layers 106 beneath it, as shown inFIG. 6. The temperature of the support and build materials (102) at thispoint in the processing is near (e.g., within 20%, 10%, 5%, etc.) of theTm (melting) temperature of the support and build materials of theprevious developed layers 102. At this temperature there is sufficientmobility of the individual polymer backbone to physically approach eachother.

While the toner resin is in this more liquid-like state, the platen 118moves to a position to receive light from the light source 124 (e.g.,ultraviolet (UV) light source) as shown in FIG. 7. Thus, in FIG. 7,light radiation from light source 124 is applied to the most-recentlytransferred developed layers 102 added on top of the previous developedlayers 106. Because only the build material 104 contains the UVphotoinitiator, only the build material 104 is UV crosslinked, leavingthe support material from development device 114, in its nominaluncrosslinked state after UV exposure. The actual temperature of UVcrosslinking depends on the exact nature of the chemical composition(molecular weight, functional groups) of the toner resin. At this point,the most-recently transferred developed layers 102 has bonded to theprevious developed layers 106 on the platen 118 and the platen is movedback to the position shown in FIG. 2, where the previous developedlayers 106 on the platen 118 are cooled to nearer Tg, after which theplaten 118 can move as shown in FIG. 3 to add an additional developedlayer 102.

FIGS. 8 and 9 illustrate an alternative 3-D electrostatic printingstructure herein which includes a planar transfuse station 138 in placeof the transfuse nip 130 shown in FIG. 2. As shown in FIG. 8, the planartransfuse station 138 is a planar portion of the ITB 110 that is betweenrollers 112 and is parallel to the platen 118. As shown in FIG. 9, withthis structure, when the platen 118 moves to contact the planartransfuse station 138, all of the developed layer 102 is transferredsimultaneously to the platen 118 or partially formed 3-D item 106,avoiding the rolling transfuses process shown in FIGS. 3-5. Similarly,as shown in FIG. 10, a drum 178 could be used in place of the ITB 110,with all other components performing as described above.

FIG. 11 is flowchart illustrating exemplary methods herein. In item 150,these methods transfer first material (e.g., build material) to a firstphotoreceptor and second material (e.g., support material) to a secondphotoreceptor using exposure and development devices. In item 152, thesemethods transfer build material from the first photoreceptor and thesecond photoreceptor to an intermediate transfer belt (ITB). The buildmaterial is the same as the support material, except that the buildmaterial includes a photoinitiator and the support material does notinclude the photoinitiator. For example, the build material and supportmaterial can comprise ultra-violet (UV) crosslinkable polymer tonersthat use the photoinitiator to crosslink.

In item 154, such processes move a platen relative to the ITB to beadjacent the ITB. These methods also heat the platen and heat a portionof the ITB that is adjacent the platen using a heater in item 156. Afterheating in item 156, such methods move the platen to contact ITB in item158 to transfer the build material and support material to the platen orto previously transferred layers existing on the platen. Successivecontacts between the ITB and platen transfer successive layers of buildmaterial and support material to the platen (each time the platencontacts the ITB) and this successively builds the 3-D object on theplaten.

In item 160, methods herein move the platen from the ITB to a heater toheat the build material and support material. In item 162, methodsherein move the platen from the heater to a light (e.g., UV lightsource) and then expose the heated build material and support materialusing the light in item 162. The processing shown in item 160 and 162 isperformed after each time the platen contacts the ITB, so as tocrosslink polymers of build material, without crosslinking polymers ofsupport material. Item 164 determines if additional layers are to betransferred to the partially completed part on the platen and, if so,processing loops back to item 150 until all successive layers are formedand the 3-D object is ready to processed further.

If not, in item 166, after all layers are transferred, subsequentprocessing removes the 3-D object of build material and support materialfrom the platen, and processing in item 168 applies solvent to the 3-Dobject using a rinsing station to dissolve only the support material andto leave the build material unaffected. The polymers of build materialbeing crosslinked and the polymers of support material not beingcrosslinked make the support material selectively soluble in the solvent(relative to the build material).

FIG. 12 illustrates many components of 3-D printer structures 204herein. The 3-D printing device 204 includes a controller/tangibleprocessor 224 and a communications port (input/output) 214 operativelyconnected to the tangible processor 224 and to a computerized networkexternal to the printing device 204. Also, the printing device 204 caninclude at least one accessory functional component, such as a graphicaluser interface (GUI) assembly 212. The user may receive messages,instructions, and menu options from, and enter instructions through, thegraphical user interface or control panel 212.

The input/output device 214 is used for communications to and from the3-D printing device 204 and comprises a wired device or wireless device(of any form, whether currently known or developed in the future). Thetangible processor 224 controls the various actions of the printingdevice 204. A non-transitory, tangible, computer storage medium device210 (which can be optical, magnetic, capacitor based, etc., and isdifferent from a transitory signal) is readable by the tangibleprocessor 224 and stores instructions that the tangible processor 224executes to allow the computerized device to perform its variousfunctions, such as those described herein. Thus, as shown in FIG. 12, abody housing has one or more functional components that operate on powersupplied from an alternating current (AC) source 220 by the power supply218. The power supply 218 can comprise a common power conversion unit,power storage element (e.g., a battery, etc), etc.

The 3-D printing device 204 includes at least one marking device(printing engine(s)) 240 that deposits successive layers of build andsupport material on a platen as described above, and are operativelyconnected to a specialized image processor 224 (that is different than ageneral purpose computer because it is specialized for processing imagedata). Also, the printing device 204 can include at least one accessoryfunctional component (such as a scanner 232) that also operates on thepower supplied from the external power source 220 (through the powersupply 218).

The one or more printing engines 240 are intended to illustrate anymarking device that applies build and support materials (toner, etc.)whether currently known or developed in the future and can include, forexample, devices that use an intermediate transfer belt 110 (as shown inFIG. 13).

Thus, as shown in FIG. 13, each of the printing engine(s) 240 shown inFIG. 12 can utilize one or more potentially different (e.g., differentcolor, different material, etc.) build material development stations116, one or more potentially different (e.g., different color, differentmaterial, etc.) support material development stations 114, etc. Thedevelopment stations 114, 116 can be any form of development station,whether currently known or developed in the future, such as individualelectrostatic marking stations, individual inkjet stations, individualdry ink stations, etc. FIG. 13 also illustrates a rinsing station 140that can apply any form of solvent to the 3-D part formed on the platen118 to dissolve and rinse away the support material without affectingthe build material.

Each of the development stations 114, 116 transfers a pattern ofmaterial to the same location of the intermediate transfer belt 110 insequence during a single belt rotation (potentially independently of acondition of the intermediate transfer belt 110) thereby, reducing thenumber of passes the intermediate transfer belt 110 must make before afull and complete image is transferred to the intermediate transfer belt110.

One exemplary individual electrostatic development station 114, 116 isshown in FIG. 14 positioned adjacent to (or potentially in contact with)intermediate transfer belt 110. Each of the individual electrostaticdevelopment stations 114, 116 includes its own charging station 258 thatcreates a uniform charge on an internal photoreceptor 256, an internalexposure device 260 that patterns the uniform charge, and an internaldevelopment device 254 that transfers build or support material to thephotoreceptor 256. The pattern of build or support material is thendrawn from the photoreceptor 256 to the intermediate transfer belt 110by way of an opposite charge of the intermediate transfer belt 110relative to the charge of the build or support material, that is usuallycreated by a charge generator 132 on the opposite side of theintermediate transfer belt 110.

While FIG. 14 illustrate five development stations adjacent or incontact with a rotating belt (110), as would be understood by thoseordinarily skilled in the art, such devices could use any number ofmarking stations (e.g., 2, 3, 5, 8, 11, etc.).

Therefore, as shown above, exemplary three-dimensional (3-D) printers204 herein include (among other components, an intermediate transferbelt (ITB 110), a first photoreceptor 256 of development unit 116transferring a first material (e.g., build material) to the ITB 110, anda second photoreceptor 256 of development unit 114 transferring a secondmaterial (e.g., support material) to the ITB 110. Thus, exposure devices260 and development devices 254 transfer build material to the firstphotoreceptor and support material to the second photoreceptor. Thebuild material is the same as the support material, except that thebuild material includes a photoinitiator, and optional crosslinkmaterial, and support material does not include the photoinitiator. Thebuild material and the support material both comprise ultra-violet (UV)crosslinkable polymer toners that use the photoinitiator to crosslink.

Such 3-D printers 204 also include a platen 118 moving relative to theITB 110 to make contact with the ITB 110. The ITB 110 transferssuccessive layers of build material and support material 102 to theplaten 118 each time the platen 118 contacts the ITB 110, and thisprocess eventually builds a 3-D object on the platen 118.

At least one heater 120 is also included in such structures, and theheater 120 heats the platen 118 and heats a portion of the ITB 110 thatis adjacent the platen 118 to the glass transition temperature of buildmaterial and support material 102 prior to the platen 118 contacting theITB 110. Another heater 122 further heats build material and supportmaterial 102 on the platen 118 to a temperature between the glasstransition temperature and the melting temperature of build material andsupport material 102 after the ITB 110 transfers build material andsupport material 102 to the platen 118, and this fuses build materialand support material 102 to previously transferred material on theplaten 118.

Such printers 204 also include a light 124 (e.g., UV light source). Theplaten 118 moves from the ITB 110 to the light 124, and then the light124 exposes build material and support material 102 on the platen 118after each time the platen 118 contacts the ITB 110, and this crosslinkspolymers of the build material without crosslinking polymers of thesupport material 102. Various systems herein include a rinsing station140 that applies solvent to the 3-D object to dissolve only the supportmaterial and to leave the build material unaffected. The polymers ofbuild material being crosslinked and the polymers of support material102 not being crosslinked makes the support material selectively solublein different solvents than the build material. As would be understood bythose ordinarily skilled in the art, the printing device 204 shown inFIG. 12 is only one example and the systems and methods herein areequally applicable to other types of printing devices that may includefewer components or more components.

While some exemplary structures are illustrated in the attacheddrawings, those ordinarily skilled in the art would understand that thedrawings are simplified schematic illustrations and that the claimspresented below encompass many more features that are not illustrated(or potentially many less) but that are commonly utilized with suchdevices and systems. Therefore, Applicants do not intend for the claimspresented below to be limited by the attached drawings, but instead theattached drawings are merely provided to illustrate a few ways in whichthe claimed features can be implemented.

As shown in U.S. Pat. No. 8,488,994, an additive manufacturing systemfor printing a 3-D part using electrophotography is known. The systemincludes a photoconductor component having a surface, and a developmentstation, where the development station is configured to developed layersof a material on the surface of the photoconductor component. The systemalso includes a transfer medium configured to receive the developedlayers from the surface of the rotatable photoconductor component, and aplaten configured to receive the developed layers from the transfercomponent in a layer-by-layer manner to print the 3-D part from at leasta portion of the received layers.

With respect to UV curable toners, as disclosed in U.S. Pat. No.7,250,238 it is known to provide a UV curable toner composition, as aremethods of utilizing the UV curable toner compositions in printingprocesses. U.S. Pat. No. 7,250,238 discloses various toner emulsionaggregation processes that permit the generation of toners that inembodiments can be cured, that is by the exposure to UV radiation, suchas UV light of has about 100 nm to about 400 nm. In U.S. Pat. No.7,250,238, the toner compositions produced can be utilized in variousprinting applications such as temperature sensitive packaging and theproduction of foil seals. In U.S. Pat. No. 7,250,238 embodiments relateto a UV curable toner composition comprised of an optional colorant, anoptional wax, a polymer generated from styrene, and acrylate selectedfrom the group consisting of butyl acrylate, carboxyethyl acrylate, anda UV light curable acrylate oligomer. Additionally, these aspects relateto a toner composition comprised of a colorant such as a pigment, anoptional wax, and a polymer generated from a UV curable cycloaliphaticepoxide.

Furthermore, U.S. Pat. No. 7,250,238 relates to a method of forming a UVcurable toner composition. The method comprises preparing a latex of apolymer formed from styrene, butyl acrylate, carboxymethyl acrylate, anda UV curable acrylate; combining the latex with an optional pigment andan optional wax to form a first system; adding flocculant to the firstsystem to induce aggregation and form toner precursor particlesdispersed in a second system; heating the toner precursor particles to atemperature greater than the glass transition temperature of the polymerto form toner particles; washing the toner particles; and optionallywashing and then drying the toner particles.

Many computerized devices are discussed above. Computerized devices thatinclude chip-based central processing units (CPU's), input/outputdevices (including graphic user interfaces (GUI), memories, comparators,tangible processors, etc.) are well-known and readily available devicesproduced by manufacturers such as Dell Computers, Round Rock Tex., USAand Apple Computer Co., Cupertino Calif., USA. Such computerized devicescommonly include input/output devices, power supplies, tangibleprocessors, electronic storage memories, wiring, etc., the details ofwhich are omitted herefrom to allow the reader to focus on the salientaspects of the systems and methods described herein. Similarly,printers, copiers, scanners and other similar peripheral equipment areavailable from Xerox Corporation, Norwalk, Conn., USA and the details ofsuch devices are not discussed herein for purposes of brevity and readerfocus.

The terms printer or printing device as used herein encompasses anyapparatus, such as a digital copier, bookmaking machine, facsimilemachine, multi-function machine, etc., which performs a print outputtingfunction for any purpose. The details of printers, printing engines,etc., are well-known and are not described in detail herein to keep thisdisclosure focused on the salient features presented. The systems andmethods herein can encompass systems and methods that print in color,monochrome, or handle color or monochrome image data. All foregoingsystems and methods are specifically applicable to electrostatographicand/or xerographic machines and/or processes.

For the purposes of this invention, the term fixing means the drying,hardening, polymerization, crosslinking, binding, or addition reactionor other reaction of the coating. In addition, terms such as “right”,“left”, “vertical”, “horizontal”, “top”, “bottom”, “upper”, “lower”,“under”, “below”, “underlying”, “over”, “overlying”, “parallel”,“perpendicular”, etc., used herein are understood to be relativelocations as they are oriented and illustrated in the drawings (unlessotherwise indicated). Terms such as “touching”, “on”, “in directcontact”, “abutting”, “directly adjacent to”, etc., mean that at leastone element physically contacts another element (without other elementsseparating the described elements). Further, the terms automated orautomatically mean that once a process is started (by a machine or auser), one or more machines perform the process without further inputfrom any user. In the drawings herein, the same identification numeralidentifies the same or similar item.

It will be appreciated that the above-disclosed and other features andfunctions, or alternatives thereof, may be desirably combined into manyother different systems or applications. Various presently unforeseen orunanticipated alternatives, modifications, variations, or improvementstherein may be subsequently made by those skilled in the art which arealso intended to be encompassed by the following claims. Unlessspecifically defined in a specific claim itself, steps or components ofthe systems and methods herein cannot be implied or imported from anyabove example as limitations to any particular order, number, position,size, shape, angle, color, or material.

What is claimed is:
 1. A three-dimensional (3-D) printer comprising: anintermediate transfer belt (ITB); a first photoreceptor transferring afirst material to said ITB; a second photoreceptor transferring a secondmaterial to said ITB, said first material is the same as said secondmaterial except said first material includes a photoinitiator and saidsecond material does not include said photoinitiator; a platen movingrelative to said ITB to make contact with said ITB at a first location,said ITB transferring successive layers of said first material and saidsecond material to said platen each time said platen contacts said ITBat said first location; a first heater heating said platen and heating aportion of said ITB that is adjacent said platen to a glass transitiontemperature of said first material and said second material prior tosaid platen contacting said ITB; a second heater at a second location,said first location where said ITB makes contact with said platen isbetween said first heater and said second heater, said second heaterfurther heating said first material and said second material on saidplaten to a temperature between said glass transition temperature and amelting temperature of said first material and said second materialafter said ITB transfers said first material and said second material tosaid platen to fuse said first material and said second material topreviously transferred material on said platen; and a light at a thirdlocation, said second heater is between said light and said firstlocation where said ITB makes contact with said platen, said lightexposes said first material and said second material on said platenafter each time said platen contacts said ITB to crosslink polymers ofsaid first material without crosslinking polymers of said secondmaterial, and said polymers of said first material being crosslinked andsaid polymers of said second material not being crosslinked makes saidsecond material selectively soluble in different solvents relative tosaid first material.
 2. The 3-D printer according to claim 1, saidplaten moving from said ITB to said light prior to said light exposingsaid first material and said second material.
 3. The 3-D printeraccording to claim 1, said first material and said second materialcomprise ultra-violet (UV) crosslinkable polymer toners that use saidphotoinitiator to crosslink.
 4. The 3-D printer according to claim 1,further comprising exposure and development devices transferring saidfirst material to said first photoreceptor and said second material tosaid second photoreceptor.
 5. The 3-D printer according to claim 1, saidITB transferring successive layers of said first material and saidsecond material to said platen building a 3-D object on said platen. 6.A three-dimensional (3-D) printer comprising: an intermediate transferbelt (ITB); a first photoreceptor transferring a first material to saidITB; a second photoreceptor transferring a second material to said ITB,said first material is the same as said second material except saidfirst material includes a photoinitiator and said second material doesnot include said photoinitiator; a platen moving relative to said ITB tomake contact with said ITB at a first location, said ITB transferringsuccessive layers of said first material and said second material tosaid platen each time said platen contacts said ITB at said firstlocation; a first heater heating said platen and heating a portion ofsaid ITB that is adjacent said platen to a glass transition temperatureof said first material and said second material prior to said platencontacting said ITB; a second heater at a second location that isdifferent from said first location, said first location where said ITBmakes contact with said platen is between said first heater and saidsecond heater, said second heater further heating said first materialand said second material on said platen to another temperature betweensaid glass transition temperature and a melting temperature of saidfirst material and said second material after said ITB transfers saidfirst material and said second material to said platen to fuse saidfirst material and said second material to previously transferredmaterial on said platen; and a light at a third location, said secondheater is between said light and said first location where said ITBmakes contact with said platen, said light exposes said first materialand said second material on said platen while said first material andsaid second material are heated to said another temperature by saidsecond heater after each time said platen contacts said ITB to crosslinkpolymers of said first material without crosslinking polymers of saidsecond material, said polymers of said first material being crosslinkedand said polymers of said second material not being crosslinked makessaid second material selectively soluble in different solvents relativeto said first material.
 7. The 3-D printer according to claim 6, saidplaten moving from said ITB to said light prior to said light exposingsaid first material and said second material.
 8. The 3-D printeraccording to claim 6, said first material and said second materialcomprise ultra-violet (UV) crosslinkable polymer toners that use saidphotoinitiator to crosslink.
 9. The 3-D printer according to claim 6,further comprising exposure and development devices transferring saidfirst material to said first photoreceptor and said second material tosaid second photoreceptor.
 10. The 3-D printer according to claim 6,said ITB transferring successive layers of said first material and saidsecond material to said platen building a 3-D object on said platen. 11.A three-dimensional (3-D) printer comprising: an intermediate transferbelt (ITB); a first photoreceptor transferring a build material to saidITB; a second photoreceptor transferring a support material to said ITB,said build material is the same as said support material except saidbuild material includes a photoinitiator and said support material doesnot include said photoinitiator; a platen moving relative to said ITB tomake contact with said ITB at a first location, said ITB transferringsuccessive layers containing both said build material and said supportmaterial to said platen each time said platen contacts said ITB at saidfirst location; a first heater heating said platen and heating a portionof said ITB that is adjacent said platen to a glass transitiontemperature of said build material and said support material prior tosaid platen contacting said ITB; a second heater at a second locationthat is different from said first location, said first location wheresaid ITB makes contact with said platen is between said first heater andsaid second heater, said second heater further heating said buildmaterial and said support material on said platen to another temperaturebetween said glass transition temperature and a melting temperature ofsaid build material and said support material after said ITB transferssaid build material and said support material to said platen to fusesaid build material and said support material to previously transferredmaterial on said platen; and a light at a third location, said secondheater is between said light and said first location where said ITBmakes contact with said platen, said light exposes said build materialand said support material on said platen while said build material andsaid support material are heated to said another temperature by saidsecond heater after each time said platen contacts said ITB to crosslinkpolymers of said build material without crosslinking polymers of saidsupport material, said polymers of said build material being crosslinkedand said polymers of said support material not being crosslinked makessaid support material selectively soluble in different solvents relativeto said build material.
 12. The 3-D printer according to claim 11, saidplaten moving from said ITB to said light prior to said light exposingsaid build material and said support material.
 13. The 3-D printeraccording to claim 11, said build material and said support materialcomprise ultra-violet (UV) crosslinkable polymer toners that use saidphotoinitiator to crosslink.
 14. The 3-D printer according to claim 11,further comprising exposure and development devices transferring saidbuild material to said first photoreceptor and said support material tosaid second photoreceptor.
 15. The 3-D printer according to claim 11,said ITB transferring successive layers of said build material and saidsupport material to said platen building a 3-D object on said platen.16. A three-dimensional (3-D) printer comprising: an intermediatetransfer belt (ITB); at least one photoreceptor transferring a firstmaterial and a second material to said ITB, said first material is thesame as said second material except said first material includes aphotoinitiator and said second material does not include saidphotoinitiator; a platen moving relative to said ITB to make contactwith said ITB at a first location, said ITB transferring successivelayers of said first material and said second material to said plateneach time said platen contacts said ITB at said first location; a heaterat a second location heating said first material and said secondmaterial on said platen to a temperature between a glass transitiontemperature and a melting temperature of said first material and saidsecond material after said ITB transfers said first material and saidsecond material to said platen; and a light at a third location, saidheater is between said light and said first location where said ITBmakes contact with said platen, said light exposes said first materialand said second material on said platen after each time said platencontacts said ITB to crosslink polymers of said first material withoutcrosslinking polymers of said second material.
 17. The 3-D printeraccording to claim 16, said platen moving from said ITB to said lightprior to said light exposing said first material and said secondmaterial.
 18. The 3-D printer according to claim 16, said first materialand said second material comprise ultra-violet (UV) crosslinkablepolymer toners that use said photoinitiator to crosslink.
 19. The 3-Dprinter according to claim 16, further comprising exposure anddevelopment devices transferring said first material to said firstphotoreceptor and said second material to said second photoreceptor. 20.The 3-D printer according to claim 16, said ITB transferring successivelayers of said first material and said second material to said platenbuilding a 3-D object on said platen.